diff options
| author | Kees Cook <keescook@chromium.org> | 2022-09-27 08:37:01 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-09-29 18:44:07 -0700 |
| commit | 7cba18332e3635aaae60e4e7d4e52849de50d91b (patch) | |
| tree | 8b18c900a236a5a65f6c612d0728687c5ef4abcd | |
| parent | 5361660af6d35f2b84926f5fcbf0491a9c21d82e (diff) | |
net: sched: cls_u32: Avoid memcpy() false-positive warning
To work around a misbehavior of the compiler's ability to see into
composite flexible array structs (as detailed in the coming memcpy()
hardening series[1]), use unsafe_memcpy(), as the sizing,
bounds-checking, and allocation are all very tightly coupled here.
This silences the false-positive reported by syzbot:
memcpy: detected field-spanning write (size 80) of single field "&n->sel" at net/sched/cls_u32.c:1043 (size 16)
[1] https://lore.kernel.org/linux-hardening/20220901065914.1417829-2-keescook@chromium.org
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Reported-by: syzbot+a2c4601efc75848ba321@syzkaller.appspotmail.com
Link: https://lore.kernel.org/lkml/000000000000a96c0b05e97f0444@google.com/
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://lore.kernel.org/r/20220927153700.3071688-1-keescook@chromium.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/sched/cls_u32.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index 58c7680faabd..0b3d909214b8 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -1040,7 +1040,11 @@ static int u32_change(struct net *net, struct sk_buff *in_skb, } #endif - memcpy(&n->sel, s, sel_size); + unsafe_memcpy(&n->sel, s, sel_size, + /* A composite flex-array structure destination, + * which was correctly sized with struct_size(), + * bounds-checked against nla_len(), and allocated + * above. */); RCU_INIT_POINTER(n->ht_up, ht); n->handle = handle; n->fshift = s->hmask ? ffs(ntohl(s->hmask)) - 1 : 0; |